There is only so much though that reading can convey, and afterwards, Leto decided to take it even further by speaking to professionals in the field of psychiatry, as well as some of their patients who were still institutionalized. Here's what Leto told Entertainment Weekly.
"There are a lot of things. It's probably better to not get into it but to the Joker, violence is a symphony. This is someone who gets an extreme reward from the act of violence and manipulation. Those are the songs he sings and he is very in tune with what makes people tick. I did meet with people that were experts, doctors, psychiatrists that dealt with psychopaths and people who had committed horrendous crimes, and then I spent some time with those people themselves, people who have been institutionalized for great periods of time. I guess when you take on a role, any role, you become part detective, part writer, and for me that's my favorite time of the entire process, the discovering, the uncovering, and the building of a character. Yeah, it's really fun."
"It was challenging but it was also fun. He has a great sense of humor, depending on who you ask. [Laughs]"
What does it say about me that I'm already a little creeped out by him, just based on his descriptions alone? It seems though that all that research went to good use, at least from the little we've seen in trailers and based on the word of his co-stars.
Suicide Squad drops on August 5th.